Current protection for battery charger

Abstract

A device includes a battery current sense circuit configured to generate a battery current feedback voltage based on a current provided to a battery, a current regulation feedback loop configured to regulate the current provided to the battery based on the battery current feedback voltage and a configurable battery current reference voltage, and a precharge regulation feedback loop configured to regulate the current provided to the battery based on the battery current feedback voltage and a configurable precharge reference voltage. The device also includes a processor configured to set the battery current reference voltage to a first value and set the precharge current reference voltage to a second value. The first value is less than the second value during a transition state.

What is claimed is: 
     
       1. A method for charging a battery, comprising:
 entering a transition state between a first charging state and a second charging state, wherein a current provided to the battery during the first charging state is less than a current provided to the battery during the second charging state; and 
 during the transition state:
 controlling a transistor to regulate a current to the battery to a first value; and 
 controlling a power converter to regulate the current to the battery to a second value, 
 wherein the first value is less than the second value. 
 
 
     
     
       2. The method of  claim 1  wherein the current provided to the battery during the second charging state is greater than the first value and the second value. 
     
     
       3. The method of  claim 1  wherein during the first state, the method further comprises:
 controlling the power converter to regulate a system voltage; and 
 controlling the transistor to prevent current from flowing to the battery. 
 
     
     
       4. The method of  claim 1  wherein during the first state, the method further comprises:
 controlling the power converter to regulate a system voltage; and 
 controlling the transistor to allow current to flow to the battery. 
 
     
     
       5. The method of  claim 1  wherein during the third state, the method further comprises:
 controlling the power converter to regulate a battery voltage; and 
 controlling the power converter to regulate the current to the battery to a value greater than the second value. 
 
     
     
       6. A method for charging a battery, comprising:
 operating a battery charger in a transition state by:
 controlling a transistor to regulate a current to the battery to a first value; and 
 controlling a power converter to regulate the current to the battery to a second value, wherein the second value is less than the first value; and 
 
 operating the battery charger in a battery current regulation state after the transition state by controlling the power converter to regulate the current to the battery to a third value, wherein the third value is greater than the second value. 
 
     
     
       7. The method of  claim 6  further comprising:
 operating the battery charger in a system voltage regulation state before the transition state by:
 controlling the power converter to regulate a system voltage; and 
 controlling the transistor to prevent current from flowing to the battery. 
 
 
     
     
       8. The method of  claim 6  wherein during the first state, the method further comprises:
 operating the battery charger in a precharge regulation state before the transition state by:
 controlling the power converter to regulate a system voltage; and 
 controlling the transistor to allow current to flow to the battery.